1. Field of the Invention
The present invention relates to data services of a complex digital cellular terminal, and more particularly, to a method for managing received data.
2. Description of the Related Art
A complex digital cellular terminal represents a combined radio communication terminal and a data processing terminal. An example of such a complex digital cellular terminal is a a CDMA (Code Division Multiple Access) terminal which can transmit and receive data by radio communication, is combined with a PDA (Personal Digital Assistant) which can manage or process data.
In order to provide a facsimile service or an asynchronous data service, the complex digital cellular terminal should have an interface for transmitting data between a radio communication terminal and a data processing terminal. Namely, there should be a radio link protocol (RLP) layer serving as the interface between an upper point-to-point protocol (PPP) layer corresponding to the data processing terminal and a lower IS95-A layer corresponding to the radio communication terminal.
The RLP layer should satisfy the TIA/EIA IS95-A, TIA/EIA IS-99 and TIA/EIA IS-657 Standards. These Standards are known in the art and therefore no further description will be given.
FIG. 1 shows a memory map for managing a frame with two variable factors, that is, a frame rate and a frame sequence number in the RLP layer. Referring to FIG. 1, a reference symbol Vn denotes a frame sequence number for designating an area in which valid frames which have been sequentially received up to now are stored, and Vr denotes a frame sequence number for designating an area in which the next frame is to be stored. Frame data stored in a buffer has a half frame rate or a full frame rate since the frame rate of the frame data is determined by an RLP frame type.
An example of data bits corresponding to the RLP frame type specified in the TIA/EIA IS-99 Standard is shown in Table 1.
As indicated in Table 1, the data size (i.e., the frame rate in bits per frame), is determined by the received RLP frame type.
If an error occurs during transmission, the data size of a frame in which an error has occurred cannot be estimated. In such a case, if the frame is processed by a full frame rate of a maximum size in order to satisfy all the frame rates, this is undesirable in that it reduces the efficiency of memory maintenance. More specifically, when a buffer of a specific size is used, it cannot be utilized efficiently.
It is therefore an object of the present invention to provide a method for managing received data by sequentially storing the received data in reception order irrespective of a frame sequence number.
It is another object of the present invention to provide a method for additionally managing an invalid frame by a negative acknowledge control table.
It is still another object of the present invention to provide a method for deleting a received frame upon receiving an invalid frame which has been previously registered in a negative acknowledge control table.
According to an aspect of the present invention, a method for managing received data by a radio link protocol layer for interfacing data between a radio communication terminal and a data processing terminal of a complex digital cellular terminal, comprises the steps of: storing data of a newly received frame in a ring-type frame content buffer in reception order and managing the stored frame by a frame control table; and registering the newly stored frame in a negative acknowledge control table when the newly stored frame and a previously stored frame do not have successive frame numbers.